Simulating webpage input

Not sure this is the best group for this post....if there is a better
group let me know.

What is the best way to simulate user input from a webpage? What I mean
is...how can I simulate the input a user would enter on a webpage and send
it to a server?

I have tried several methods with mixed results. I usually end up
analyzing cookies and http headers and many times I get lost or give up.

I am using visual basic. I have used both cgi and http requests to
simulate what is going on....but like I said..many times I get lost.

Sooo...now I set back and ask...are these the BEST ways to do this? Its
more like reverse engineering than programming.

Might it be possible to save the webpage html and insert the client input
into it and send it via the webbrowser or something along those lines?

This would save me from getting lost in reverse engineering what is going
on with sniffers etc. Just make the input look the same as a user's input.
I am thinking there MUST be a better way to do this.

Ideas or suggestions?

TIA
Bob